This snippet was orginally taken from Help understand Click to View Object Script

using UnityEngine;
using System.Collections;

public class ChangeLookAtTarget : MonoBehaviour {

    public GameObject target; // the target that the camera should look at

    void Start() {
        if (target == null) 
        {
            target = this.gameObject;
            Debug.Log ("ChangeLookAtTarget target not specified. Defaulting to parent GameObject");
        }
    }

    // Called when MouseDown on this gameObject
    void OnMouseDown () {
        // change the target of the LookAtTarget script to be this gameobject.
        LookAtTarget.target = target;
        Camera.main.fieldOfView = 60*target.transform.localScale.x;
    }
}